1. Field of the Invention
The present invention relates to a vibratory gyroscope, and particularly to a vibratory gyroscope which is capable of measuring a rotational angular velocity by utilizing, for example, a bending and vibration mode, and is used, for example, in a navigation system installed in an automobile.
2. Description of the Prior Art
FIG. 24 is a perspective view showing an example of a conventional vibratory gyroscope which is a background of the present invention, and FIG. 25 is a circuit diagram thereof. The vibratory gyroscope 1 comprises a vibrator 2. The vibrator 2 includes a triangular prism-shaped vibrating body 3, on three side faces of the vibrating body 3, piezoelectric elements 4a, 4b and 4c are formed respectively. Supporting members 5a and 5b, consisting of a material such as nickel or the like, are fixed to ridge-line portions of the vibrating body 3. The supporting members 5a and 5b are fixed to the vicinity of nodal points of the vibrating body 3 by means of soldering, welding or the like. Furthermore, the supporting members 5a and 5b are fixed to a board 6 by means of soldering or the like. The supporting members 5a and 5b support the vibrating body 3 above the board 6 in a vibratory fashion and also serve as wires for grounding.
Meanwhile, one piezoelectric element 4c of the vibrator 2 is electrically connected to an input terminal of an oscillation circuit 7, output terminals of the oscillation circuit 7 are electrically connected to the other two piezoelectric elements 4a and 4b. Thus, the vibrator 2 makes self-oscillation drive. The two piezoelectric elements 4a and 4b are also electrically connected respectively to two input terminals of a detection circuit 8 consisting of, for example, a differential amplifier.
In the vibratory gyroscope 1, by applying a driving signal to the piezoelectric elements 4a and 4b, the vibrating body 3 bends and vibrates. When the vibratory gyroscope 1 is rotated about an axial direction of the vibrating body 3, voltages are generated in the piezoelectric elements 4a and 4b responsive thereto. And hence, by measuring the voltages generated in the piezoelectric elements 4a and 4b, a rotational angular velocity can be detected. Thus, the rotational angular velocity of the vibratory gyroscope 1 is detected by an output of the detection circuit 8.
In such a conventional vibratory gyroscope, the supporting members are designed to support the vibrating body and to serve as the wires for grounding. Hence, as a conductive substance having a solderability and a weldability, a metal wire such as nickel is used. However, nickel or the like is relatively mild, thus when a thin wire material is used, the mechanical strength thereof is weakened. When a thick wire material is used as the supporting members, the vibration of the vibrating body may leak, or an outside vibration is transmitted through the supporting members, thereby deteriorating characteristics stability.
Therefore, it is considered to manufacture the supporting members with a material having a large strength such as molybdenum. However, such material is difficult to be soldered or welded and can not support the vibrating body.
In such conventional vibratory gyroscope, the vibrator is susceptible to an outside magnetism and its characteristics is deteriorated by the outside magnetism.
Furthermore, in such a conventional vibratory gyroscope, when a large inertial force is exerted on the vibrator, sometimes the supporting members for supporting the vibrator are exposed to plastic deformation, thus in such a case characteristics are deteriorated.